Experimental and theoretical investigation on the inhibition performance of disulﬁde derivatives on cobalt corrosion in alkaline medium
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Cobalt, as the barrier layer material for 14 nm copper interconnection, has been widely applied owing to its superior characteristics of low resistivity, excellent adhesion performance and blocking properties for copper. Most of the preciously developed cobalt corrosion inhibitors under weak alkaline condition are toxic, low water solubility, and limited to traditional experimental research. In this work, 3,3-dithiodipropionic acid (DDA), 2,2-dibenzamidodiphenyl disulﬁde (DPD) as potential corrosion inhibitors for cobalt in NH4Cl and H2O2 media under alkaline environment were investigated. Electrochemical experiments, surface morphology characterization, quantum chemical calculation and molecular dynamic simulation were combined to analyze the corrosion inhibition ability and mechanism. The experimental and theoretical results present that these disulﬁde derivatives can inhibit the corrosion behavior of cobalt surface effectively in ammonium-based aqueous solutions. When the concentration of inhibitors was 0.5 wt%, the corrosion inhibition efﬁciency of DDA, DPD reach up to 92.9%, 91.41%, respectively. Their favorable capability is attributed to the dense adsorption ﬁlms following the Langmuir adsorption isotherm. Besides, these two inhibitors show excellent performance of galvanic cor-rosion inhibition at the Co/Cu interface, which is consistent with the shift tendency simulations for bind-ing to Co/Cu substrates. The results of water solubility and toxicity tests indicate that DDA is more suitable for industrial applications.